1. Field of the Invention
The present invention generally relates to fabrication of liquid crystal display (LCD), and more particularly to a transport apparatus used in a cleaning process of LCD cells.
2. Description of the Related Art
In the LCD manufacturing process, two glass substrates are joined with seal material, and liquid crystal (LC) material is injected into the small space therebetween. Next, polarizing films are attached onto the outside of each substrate and the driver electronic PWBs are attached thereon. Finally, a backlight unit is added to complete the LCD module.
Specifically, the glass substrates are assembled by the following steps. First, an adhesive seal material is applied, usually by either silkscreening or screen printing. An opening is left in the seal for LC material injection in the subsequent process. After the adhesive is applied, it is cured in order to outgas solvents in the material and achieve partial cross-linking of the polymer. This makes the material less tacky (B-stage material), which allows the substrates to contact with each other during alignment. Before assembling the two substrates, spacers are deposited on one of the substrates to maintain a precise cell gap (between 5-10 micrometers) between the two substrates. The substrates are then aligned and laminated by heat and pressure to complete the cross-linking of the polymer.
After the assembling process is completed, the assembled glass substrates are cut into individual LCD cells. The LC material is injected into the gap produced by the spacer. The opening that was left open for this injection is sealed with the same type of resin and cured. Finally, polarizers, typically in precut sheets, are attached onto the outside of each LCD cell through an adhesive layer that is already on one side of the polarizers.
A cleaning process for cleaning the LCD cells is essential in the fabrication of LCD devices, e.g., after injection of LC material or before the attachment of polarizers. Such a cleaning process generally includes a chemical treatment process in which the LCD cells are immersed in a chemical liquid for surface treatment and a rinse process in which the LCD cells are immersed in tap water and pure water for removing the residual chemical liquid from the surface of the LCD cells.
FIG. 1 shows a conventional LCD cell transport apparatus 100 for transporting a cleaning basket 110 loaded with LCD cells 120 from one cleaning sink 130 to another in a cleaning system. The LCD cell transport apparatus 100 includes a transfer robot arm 102 having a base 102a. The base 102a is usually configured to have a flat surface for supporting the cleaning basket 110. Therefore, when the transfer robot arm 102 takes out the cleaning basket 110 from the cleaning sink 130, liquids (such as chemical liquid, tap water and pure water) tend to remain in the notch 120a of LCD cells 120 thereby adversely affecting the drying quality. Further, it is easy to find impurities remained in the seam of the glass substrates of the LCD cells 120 after drying. These impurities have adverse effect on the quality of the cleaning process.
In manufacturing LCD device, the yield and the quality of the products are remarkably lower if contaminants such as impurities adhere to the LCD cells 120. Accordingly, there exist the needs for improving the cleaning quality for the LCD cells.
It is a primary objective of the present invention to provide a liquid crystal display (LCD) cell transport apparatus capable of greatly enhancing the quality of the cleaning process.
In accordance with the above object, we discloses a LCD cell transport apparatus comprising a transfer robot arm having a base for supporting and transferring a cleaning basket loaded with LCD cells. The LCD cell transport apparatus is characterized in that the three corners of the base are respectively provided with spacers, wherein each of the spacers has a thickness different from one another. When the cleaning basket with LCD cells disposed therein is placed on the base, the cleaning basket has a comer at a level lower than the other comers. Therefore, when the transfer robot arm takes out the cleaning basket with LCD cells from liquid in the cleaning sink, the residual liquid on the surface of the LCD cells will gather up and flow to the comer at the lowest level, thereby minimizing the retention of liquid upon the LCD cell.